1. Field of the Invention
The present invention relates to a composition for forming a conductive film and a method for forming wiring or an electrode on a substrate by use thereof. More specifically, it relates to a conductive film forming method which can be suitably used in formation of wiring or an electrode for an electronic device.
2. Description of the Related Art
Aluminum is used as a wiring material used in a number of electronic devices such as a solar cell, a semiconductor device and an electronic display device. Heretofore, it has been generally practiced that such an aluminum film is formed by a vacuum process such as sputtering, vacuum deposition or CVD and the obtained aluminum film is then processed into an aluminum pattern by photo-etching using a resist. However, this method is disadvantageous from the viewpoint of energy consumption since it requires a large-scale vacuum deposition apparatus. Further, since it is difficult to form aluminum wiring uniformly on a large-area substrate by this method, a yield is poor, causing an increase in costs.
Meanwhile, in recent years, a paste which has fine aluminum particles dispersed in a binder has been developed, and a method of forming a pattern of aluminum by pattern-printing the paste by, e.g., screen printing, and baking the printed paste has been reported (JP-A 10-335267) (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). This method can be carried out at a low cost because it deals with direct patterning by printing of the aluminum paste. However, obtained aluminum is liable to contain impurities, an aluminum pattern with a low resistance is difficult to obtain, and formation of a fine pattern by the method is difficult from a technical standpoint.
Further, a method has been developed that comprises coating a solution of a specific organic aluminum compound by, e.g., spin coating so as to form a coating film and baking the film so as to form a conductive film. In this method, organic components of the organic aluminum used and a solvent used scatter, thereby making the obtained film inevitably liable to have a lower density than a film formed by a vacuum method such as sputtering. Accordingly, when a high-density film is required as in the case where the obtained film is used as a conductive film, the low density of the film obtained by the above method may be a problem.